The present invention relates to an air-fuel ratio controller of an internal-combustion engine for causing evaporated fuel produced within a fuel tank to be sucked into an air intake side of the internal-combustion engine and be burned.
As a conventional controller which stores evaporated fuel produced within a fuel tank in a canister and discharges the evaporated fuel stored in the canister into an air intake side of an internal-combustion engine to burn it, there is a controller which changes a purge amount of the canister by a predetermined value and detects a concentration of the evaporated fuel sucked into the air intake side of the internal-combustion engine from the canister on the basis of a variation of a feedback amount of an air-fuel ratio at this time to correct a learning value of the air-fuel ratio in accordance with the concentration (for example, JPA-2-130240).
The conventional controller described above has a problem that the air-fuel ratio tends to be excessive in the beginning of the purging since the concentration of the evaporated fuel is high in the beginning of the purging and is not detected exactly yet. U.S. Ser. No. 08/052,926 filed on Apr. 27, 1993, now U.S. Pat. No. 5,299,546, and U.S. Ser. No. 08/079,807 filed on Jun. 22, 1993, still pending, were entitled "air-fuel ratio control apparatus for internal combustion engine" and assigned to the present assignee.